akiyoshi kitaoka* and hiroshi ashida** - 立命館大学akitaoka/pdrift.pdf · -261 - (vision...
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■ (VISION Vol.15, No.4, 261-262, 2003)
Akiyoshi KITAOKA* and Hiroshi ASHIDA**
* Department of Psychology, College of Letters, Ritsumeikan University
56-1 Toji-in Kitamachi, Kita-ku, Kyoto 603-8577, Japan
** Graduate School of Letters, Kyoto University
Yoshida-honmachi, Sakyo-ku, Kyoto 606-8501, Japan
The peripheral drift illusion refers to an
anomalous motion illusion that can be observed in
peripheral vision 1-3)(Fig. 1). Although this illusion
has been characterized by gratings that have
sawtooth luminance profiles, we demonstrate that
ones with stepwise profiles are more effective.
Moreover, the order of four regions of different
luminances is critical, i.e. the combination of black
and dark-gray or the combination of white and
light-gray. Specifically, illusory motion tends to
appear in the direction from a black region to an
adjacent dark-gray region or in the direction from
a white region to an adjacent light-gray region
(Fig. 2). This order enhances the peripheral drift
illusion as shown in Fig. 3.
We point out two novel factors that affect the
strength of illusory motion.(1)The peripheral
drift illusion is enhanced by stepwise luminance
profiles, as mentioned above. Stimuli with smooth
luminance profiles, like Fig. 1, give weaker illusion.
(2)The peripheral drift illusion is enhanced by
fragmented or curved edges. Stimuli made up of
long edges give weaker illusion. Fig. 4 is produced
Fig.1 The peripheral drift illusion. When observers seethis figure in the peripheral vision, the circle appearsto rotate slowly. Although Fraser and Wilcox 1)
reported that the direction of illusory rotation wasclockwise or counterclockwise depending onindividuals, recent studies 2, 3)mentioned only clockwiserotation in this case.
Fig.2 The phenomenal rules of the peripheral driftillusion we here propose, i.e. black to dark-grayand white to light-gray. Arrows indicate assumedlocal motion signals and their strengths, whichoriginate from black or white areas.
Fig.3 Enhancement of the peripheral drift illusion by ournew rules. When observers see this figure in theperipheral vision, the circle appears to rotate clockwise.This illusory rotation is stronger than that in Fig. 1.VSJ summer meeting 2003(21 July)
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according to these rules and shows illusory rotation
even stronger than that in Fig. 3. There are a variety
of applied figures of the peripheral drift illusion on
the first author's webpage: http://www.ritsumei.ac.jp/
~akitaoka/index-e.html.
Although this study only reveals phenomenological
or design rules to obtain the peripheral drift illusion
with large illusion magnitude, we are seeking an
explanation on the basis of motion detector models 4).
It is also expected that these rules can contribute to
the study of motion perception to elucidate anomalous
motion illusions 5-11) such as the Ouchi illusion(Fig. 5).
Acknowledgment.
This research was supported by Grant-in-Aid(the
Heisei 14th grant entitled "Internet edutainment using
anomalous motion illusions")awarded from the Hayao
Nakayama Foundation for Science, Technology and
Culture, and Grant-in-Aid for Scientific Research
(Nos. 14310036 and 14310045)awarded from the
Japan Society for the Promotion of Science.
References
1 ) A. Fraser and K. J. Wilcox: Perception of illusory
movement. Nature, 281, 565-566, 1979.
2 ) J. Faubert and A. M. Herbert: The peripheral drift
illusion: A motion illusion in the visual periphery.
Perception, 28, 617-621, 1999.
3 ) G. Naor-Raz and R. Sekuler: Perceptual dimorphism
in visual motion from stationary patterns. Perception,
29, 325-335, 2000.
4 ) H. Ashida and A. Kitaoka: A gradient-based model
of the peripheral drift illusion. Perception, 32
(supplement), 106.
5 ) H. Ouchi: Japanese optical and geometrical art.
Dover, Mineola NY, 1977.
6 ) L. Spillmann, F. Heitger and S. Schuller: Apparent
displacement and phase unlocking in checkerboard
patterns. Paper presented at the 9th European
Conference on Visual Perception, Bad Nauheim,
1986.
7 ) T. J. Hine, M. Cook and G. T. Rogers: An illusion of
relative motion dependent upon spatial frequency
and orientation. Vision Research, 35, 3093-3102, 1995.
8 ) T. J. Hine, M. Cook and G. T. Rogers: The Ouchi
illusion: An anomaly in the perception of rigid
motion for limited spatial frequencies and angles.
Perception and Psychophysics, 59, 448-455, 1997.
9 ) B.-G. Khang and E. A. Essock: Apparent swinging
motion from a 2-D sinusoidal pattern. Perception,
29, 453-459, 2000.
10 ) B. Pinna and G. J. Brelstaff: A new visual illusion of
relative motion. Vision Research, 40, 2091-2096, 2000.
11 ) H. Ashida: Spatial frequency tuning of the Ouchi
illusion and its dependence on stimulus size. Vision
Research, 42, 1413-1420, 2002.
Fig.5 The Ouchi illusion, the most typical among anomalousmotion illusions. The inset appears to move whilethe surround does not.
Fig.4 Further enhancement of the peripheral drift illusionby our further rules. When observers see this figurein the peripheral vision, the circle appears to rotateclockwise. This illusory rotation is even strongerthan that in Fig. 3.